Research On Key Technologies Of Quality Oriented Product Manufacturing Process Optimization

In the product manufacturing process,machining and assembly are the main tasks of product manufacturing.Therefore,product quality is not only related to product design,but also depends on machining quality of parts and assembly quality of product,i.e.,quality of manufacturing process has a great influence on product quality.Thus,in order to ensure reliability and stability of product quality,the product not only requires functional parts with high machining precision during machining,but also achieves the best overall performance on the basic of high precision,high efficiency and high stability assemblies during assembly.This thesis which is based on product manufacturing process with high quality requirement,focuses on high precision laser micromachining technology and selective assembly technology,and proposes key technologies for quality optimization during machining and assembly of product.The main research contents are as follows:Based on the analysis of characteristics,uncertainty and quality factors of product manufacturing process with high quality requirement,the quality optimization system,which consists of basic data layer,data application layer and software interaction layer,is constructed from the perspective of theoretical research and system implementation.The key technologies for quality optimization are also identified in each stage of product manufacturing process with high quality requirement.Taking the machining process of high precision parts in product with high quality requirement as the research object,a new type of multistep laser micro-machining scheme is proposed.Under the goal of optimal quality and cost,the optimization model of the unit machining cost is constructed and the improved particle swarm optimization algorithm is applied to solve the model.The results of numerical simulation and case validation show that compared with the traditional laser machining scheme,the proposed scheme can greatly improve the qualification rate of parts and simultaneously reduce the unit machining cost.Taking the assembly process of non-normal distributed parts in product with high quality requirement as the research object,a new type of grouping selective assembly scheme is proposed.The objective function for selective assembly is established,and the improved genetic algorithm is used to solve the problem.The results of numerical simulation show that the proposed scheme can greatly enhance the pass rate of products and reduce the surplus parts compared with the traditional grouping selective assembly scheme.Taking the assembly process of multi-dimension characteristics parts in product with high quality requirement as the research object,a new type of accurate selective assembly scheme is proposed.The multi-objective quality loss function is established based on the improved Taguchi quality loss model.The improved NSGA-? algorithm is used to solve the problem.The results of numerical simulation show that the proposed scheme can achieve multi-objective optimization for the assembly quality loss problem of multi-dimension chain and multi-dimension characteristics,and improve the stability of assembly dimension precision in the assembly process of multi-dimension characteristics parts.Taking the final assembly process of multivariate quality characteristics parts in product with high quality requirement as the research object,a new type of accurate selective assembly scheme is proposed.A new Taguchi quality loss model is constructed by using signal to noise ratio.The improved SPEA2 algorithm is used to solve the model.The results of numerical simulation show that the proposed scheme can achieve multi-obj ective optimization for the assembly quality loss problem of multi-dimension chain and multivariate quality characteristics,and improve the stability of product quality in the final assembly process of multivariate quality characteristics parts.